The present invention relates to a vehicle seat, such as a car seat.
The predominant method for the manufacture of vehicle seats is to cast the seat together with optional inserts made of steel etc., in one and the same material, usually foamed polyether cellular plastic. The seat cushion should be comfortable, while the sides which are supposed support the thighs shall be somewhat harder. This is achieved by foaming, in the same mould, with different indexes, i.e. different amounts of isocyanate are used. More isocyanate gives a harder cellular plastic. Such a foam material does not absorb any energy, but instead results in a quick spring back.
As part of the personal protection in modern cars the seats, especially the front seats, are made stiffer in order not to break in an accident. This type of seats give a better protection at higher speeds, but they work less good at low speeds. Because of the stiffness, the seat will not absorb energy at for example a rear-end collision at low speed, but instead the body and especially the head will bounce back and forward resulting in so called whip-lash injuries in the vertebral column. The insurance companies have established that the number of injuries increases every year, and in Sweden now about 16,000 injuries are reported each year, and about 2,000 of these lead to invalidity.
The object of the present invention is to provide a vehicle seat having energy absorbing characteristics which compared to the prior art exhibits enhanced protection against whip-lash injuries at rear-end collisions.
This and other objects of the invention are achieved with the vehicle seat according to the invention.